A kelly spinner is a well known tool for making up a joint of drill pipe by application of a fixed amount of torque. Use of a kelly spinner can significantly reduce the time required for the joint makeup operation and the potential of spark formation and lost fingers in comparison to spinning chains previously employed.
Kelly spinners typically comprise a geared mandrel having suitable pipe connections at each end. The mandrel is installed in the string between a derrick swivel and a kelly joint. A motor then turns the mandrel which in turn spins the kelly joint to makeup a new joint on the kelly opposite end.
In some circumstances, it is not desirable to insert the spinner mandrel in the drill string due to space limitations. In such instances, the spinner mandrel can be removed and the ring gear of the spinner is attached directly to a swivel stem. In one commercial version, the ring gear was secured to a collar which fit around the swivel stem. The collar was held in place by a plurality of radially spaced set screws threaded transversely through the collar to engage the swivel stem in coaxial alignment. Such screws have proved inadequate for preventing axial play along the swivel stem because the spinner gear was difficult to install without radial misalignment. Even with proper alignment during installation, the set screws were axially offset from the ring gear and could not maintain good alignment during operation. Run-out in the gear usually resulted in an eventual loosening of the screws. Axial play often caused the spinner gear to slip along the stem and disengage from an intermeshing motor pinion gear.
Consequently, there is a need in the art for a means for attaching the spinner gear to the swivel stem which ensures radial alignment to the swivel stem and avoids play in the axial direction.